The biosynthesis of porphyrins, corrins, heme and chlorophyll will be studied by C13-FT NMR spectroscopy at the whole cell and cell free levels. The structure of cobalt-free corrinoids will be determined. Large samples of C13 labeled ALA and PBG will become available for studying porphyria. BIBLIOGRAPHIC REFERENCES: Biosynthesis of Uroporphyrinogen III from Porphobilinogen. Resolution of the Enigmatic "Switch" Mechanism. A. Ian Scott, K.S. Ho, M. Kajiwara, T. Takahashi. J. Amer. Chem. Soc., 98, 1589 (1976). The Methylation Process in Corrin Biosynthesis. Application of H1(C13) PMR Difference Spectroscopy to a Biochemical Problem. A. Ian Scott. M. Kajiwara, T. Takahashi, Ian M. Armitage, P. Demou, and D. Petrocine, Chem. Comm. (1976).